<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button>点击停止定时器</button>
    <script>
        /* 
           清除定时器：
           clearTimeout(定时器的名字);
        */
       var timer = setTimeout(() => {
           console.log('HELLO WORLO');
       },5000);
       var button = document.querySelector('button');
       button.addEventListener('click',function(){
           console.log("123");
           clearTimeout(timer1);
       });
    </script>
</body>
</html>